Means for starting portable power units



` March 2`1,1939.fv L J. w. l-"llrzy GERALD 2,151,196

MEANS FOR STARTING PORTABLE POWER UNITS Filed Dec. Q 1937 V #mm-uh I 3.

JUN*

Patented Mu. 2i, resa i UNITED STATES .PATENT OFFICE John W. Fitz Gerald, Milwaukee, Wis., signor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application December 9, 1937, Serial No. 178,947

4 Claims.

This invention relates to portable power units, and refers particularly to means for starting such units.

Portable power units of the type to which this invention pertains consist of an internal combustion engine, generally of the small readily portable single cylinder type, and a motor-generator directly coupled thereto. "I'he motor-generator is connected to a battery through a conventional cutout to maintain the battery charged and supply a source of electric current for use on farms and other places where commercial power is not available.

In these small units, it is obviously desirable to keep the cost and weight down as low as possible. The smallest motor-generator capable oi the rated output of the unit is therefore used.

If the requirement for small size and low cost were not to be contended with in the selection of the motor-generator, starting of the engine would present no problems for it would then be necessary merely to close a starting switch which would connect a starting winding in the motorgenerator unit across the battery. However. when the motor-generator is held down to a size small enough to meet the above prerequisites, it has insuilicient torque to carry the engine over compression.

It is therefore an object of this invention to provide a starting device for portable power units oi this type wherein the insuflicient power of the motor-generator is augmented during the initial cranking period.

More specifically it is an object of this invention to provide a starting device for portable power units of the character described wherein a starting member like a foot pedal is provided to permit manual cranking of the engine and wherein the starting winding of the motor-generator is connected across the battery in consequence to the manual actuation of the starting or cranking member.

It is also an object of this invention to provide an extremely simple switch construction for closing the starting circuit of the motor-generator upon actuation of the foot pedal or other manually operable cranking member.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described, and more particularly deiined by the appended claims, it being understood that such changes in the precise embodi- (Cl. 29o-31) ment of the hereindisclosed invention may be made as come within the scope of the claims.

'I'he accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed in accordance with the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a side elevational view of a portablev `bustion engine of the single cylinder type mounted on a base 6 and having its crankshaft (not shown) coupled to the armature shaft l of a motor-generator 8 which is also mounted on the base 6. i

Pivoted on a stud 9 carried by the crankcase I of the engine is a manually operable starting member in the form of a foot pedal II. This pedal carries a gear segment I2 adapted to mesh with a pinion I3 which is drivingly connected with the crankshaft of the engine through a clutch of conventional construction housed within a pulley I4. The pedal II is loosely pivoted on the stud 9 as is also a lever I5 mounted alongside the pedal.

This lever I5 is yieldingly urged in a counterclockwise direction by a torsion spring I6 coiled about the stud 9 and having one end engaging the lever and its other end anchored in any suitable manner. The outer end of the lever engages the top of the hub I1 on the crankcase to limit its spring propelled motion, and the opposite end of the lever is clamped to the side of the pedal by a bolt I8.

The bolt I8 is fixed to the lever and passes through an arcuate slot I9 in the foot pedal so as to permit the pedal to be swung to an upright inoperative position, it being understood that the clamping bolt incorporates a suitable spring washer to permit such movement of the pedal.

However, when the pedal is swung down to its position shown in Figure 2, the bolt engages the end of the slot I9 so that by stepping down on the end of the pedal, not only is its gear segment I 2 engaged with the pinion to rotate the same, but the lever I5 is also carried about the stud I against the tension of the spring I5. Consequently, upon releasing the foot pedal, the spring Il returns the same to its inoperative position shown in Figure 2.

It is to be observed that the bolt Il has a projecting end 20. This projecting end of the bolt engages under and lifts one spring finger 2| oi' a starting switch BS. This spring finger or blade is biased downwardly toward engagement with a cooperating spring blade or finger 22. The blades or spring fingers 2| and 22 thus constitute the starting switch BS, and these blades or iingers are mounted in any suitable manner as by being riveted to a block of insulating material 22 ilxed to the side oi.' the motor-generator, as shown in Figure 1.

The relationship of the parts is thus such that when the foot pedal is in its normal spring retained inoperative position, the starting switch SS is open, but the instant the foot pedal is depressed to crank the engine, the starting switch SS closes, Closure of the starting switch connects a starting winding 25 across the battery B, which is arranged to be charged during operation oi the power unit. The manner in which this is accomplished is clearly illustrated in the diagrammatic disclosure of Figure 3.

As shown in this diagram, the motor-generator has one side of its field and armature windings grounded and has the other side thereof connected to one side of the starting winding and also to a conventional cutout 26. Through the cutout 2l, the eld winding is connected to one side of the battery, the other side of which is grounded.

The starting switch SS is connected between the opposite end of the starting winding and the ungrounded side of the battery so that when the switch SS is closed, current ows from the battery through the starting winding and then through the eld winding to the ground.

Hence, it will be seen that by stepping down on the pedal the engine is initially turned over and the motor-generator is connected with the battery, so that acting as a motor, it continues to spin the engine as long as the pedal 1s held depressed. When the engine starts, the pedal is allowed to return to its inoperative position, and as it does, it reopens the switch SS and disconnects the starting winding from the battery.

After the unit is in operation and sufficient voltage is built up in the neld winding, the cutout 26 functions to connect the motor-generator with the battery to charge the same.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent to those skilled in the art that this invention makes possible the use of a small inexpensive motor-generator in a portable power unit of the character described, and that it entirely overcomes the inability of such a small motorgenerator to crank the engine by providing manually operable means to carry the engine over compression.

What I claim as my invention is:

1. Means for starting portable power units of the type wherein an internal combustion engine is drivingly connected with a motor-generator and wherein a battery is electrically connected with the motor-generator when the unit is in operation comprising: a starting winding for the motorgenerator; an electric starting'crcuit for c'onnect ing the starting winding with the battery so that the motor-generator acting as a motor cranks the engine; a mechanical starting member di rectly connected with the engine whereby the engine may be manually cranked; and means for closing said starting circuit as a consequence to cranking actuation of the starting member.

2. Means for starting portable power units of the type wherein an internal combustion engine is drivingly connected with a motor-generator and wherein a battery is electrically connected with the motor-generator when the unit is in operation comprising: a starting winding for the motor-generator; an electric starting circuit for connecting the starting winding with the battery so that the motor-generator acting as a motor cranks the engine; a foot pedal; means for connecting the foot pedal with the engine whereby depression of the pedal cranks the engine; a switch in the starting circuit; and means whereby said switch is closed upon depression of the pedal.

3. Means for starting portable power units of the type wherein an internal combustion engine is drivingly connected with a motor-generator and wherein a battery is electrically connected with the motor-generator when the unit is in operation comprising: a starting winding for the motor-generator; an electric starting circuit for connecting the starting winding with the battery so that the motor-generator acting as a motor cranks the engine; a starting member connected with the engine whereby the engine may be manually cranked; means for yieldingly holding the starting member in an inoperative position ready for manual actuation; an electric switch in the starting circuit; means connected with the starting member for holding the switch open as long as the starting member is in its inoperative position; and means for closing the switch upon cranking actuation of the starting member.

4. In combination with an internal combustion engine: a starting member movable to crank the engine; an electric motor-generator connected with the engine having a starting winding which when connected with a source of electrical energy energizes the motor-generator and applies a starting torque on the engine; and an electric switch for connecting the starting winding with a source of electrical energy controlled by the starting member to be closed upon cranking actuation thereof.

JOHN W. FI'Z GERALD. 

